I bought one for my sister for Chrissy (a nice pink one - 'cause she hates pink) because she is completely directionally challenged. She does a lot of travelling O/S for work so she ends up either staying in the hotel or paying for taxis. This way she can now go for a walk at least and find her way back!
We played with it around the house and it worked fine. So if all you want to do is go for a stalk and find your way back to the car, it should be fine. If you want to mark points of interest, or keep a log of where you walked, etc, like other GPS's can, then you won't be able to use the backtracker.
Also, you'd want to be VERY VERY careful that you didn't accidentally overwrite your car position while out stalking!!! For that reason alone, I'd never use one in the bush. Too risky.